Reduction of soil weedseedbank with increased yield in dry direct-seeded rice through weed management

Abstract

Rice cultivation always have a significant role in food and livelihood security. The predictions of increasing water deficiency under a changing climate and overcoming labor shortages in agriculture have brought a change in rice cultivation from conventionally flooded transplanting to direct-seeded rice (DSR) but weeds are the major production constrain in direct-seeded rice. Keeping these facts in view a field study was conducted during rainy season (Kharif), 2016 and 2017 at the Main Research Station, Hebbal, Bengaluru, India to study the effect of different weed management treatments in dry direct-seeded rice (upland condition) on growth, yield and soil weed seedbank as measured by emergence of weed seedlings. Among various weed management treatments, hand weeding at 20, 40 and 60 DAS recorded significantly highest paddy grain and straw yield in hand weeding at 20, 40 and 60 DAS (5.50 and 7.22 t/ha, respectively) and found at par with application of bensulfuron-methyl + pretilachlor as pre-emergence fb bispyribac-sodium (5.39 and 7.16 t/ha, respectively). Weedy check recorded significantly lowest yield (1.40 and 2.32 t/ha, respectively). At different intervals significantly the lowest weed seedlings emergence was noticed from the soils collected from different depths in hand weeded plots during both the years. Among various herbicide combinations, pre-emergence application of bensulfuron-methyl + pretilachlor followed by bispyribac-sodium recorded the lowest weed seedbank, as measured by germination of weed seeds and weed seedling emergence, followed by bensulfuron-methyl + pretilachlor and triafamone + ethoxysulfuron. Significantly the highest weed seedbank was noticed from soil collected from weedy check.